This invention relates generally to gas turbine components, and more particularly to turbine airfoils.
A gas turbine engine includes a compressor that provides pressurized air to a combustor wherein the air is mixed with fuel and ignited for generating hot combustion gases. These gases flow downstream to one or more turbines that extract energy therefrom to power the compressor and provide useful work such as powering an aircraft in flight. In a turbofan engine, which typically includes a fan placed at the front of the core engine, a high pressure turbine powers the compressor of the core engine. A low pressure turbine is disposed downstream from the high pressure turbine for powering the fan. Each turbine stage commonly includes a stationary turbine nozzle followed in turn by a turbine rotor, each of which includes a plurality of hollow airfoils which are cooled by a combination of internal convective cooling and gas side film cooling.
For reasons of aerodynamic efficiency, the high pressure turbine blades or nozzles typically have thin trailing edges and therefore can not accommodate convection cooling openings (i.e. holes or slots) extending all the way to the end of the trailing edge. These openings typically break out from the pressure side surface upstream of the trailing edge. The cooling air leaving the openings mixes with some of the external hot gases and becomes film cooling to protect the downstream trailing edge surface. Slot film cooling typically is the only cooling mechanism for the very aft end of the trailing edge. Trailing edge slots are typically discrete and separated with partition walls. The partition walls are extended outside the slots to form so-called lands. The lands have a tapered height in an axial direction and provide structural support for the trailing edge. These lands are exposed to the hot gas on pressure side and receive a very limited amount of film cooling spilled over from the slots. Therefore, the lands are typically much hotter than the suction side wall on the slot floor between lands. Accordingly, there is a need for providing cooling for these lands.